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Thursday, December 6, 2012

GIS, General Lee, and the Future of Historical Cartography

Unless you’re a
professional geographer, you’ve probably never heard of a tool called
Geographic Information Systems, or GIS. Until recently, unless you were a
student or faculty member at Middlebury College in Middlebury, Vermont, you may
not have heard of Associate Professor of Geography Anne Kelly Knowles. Readers
of the December issue of “Smithsonian” magazine know her as one of the
recipients of the 2012 American Ingenuity Awards, given to individuals recognized
for “brilliant new achievements in science, technology, art and society.”

According to the GIS
website, the program allows geographers to take location-related data,
integrate it onto a map, globe or chart, and analyze and display relationships
and trends over a geographic space. I realize that this doesn’t sound very
exciting. But the way that this program is being used takes it out of the
functional realm of Cartography and into a variety of different fields, including
History.

Using the GIS program,
Professor Knowles has made new connections between geography and history,
applying historical data to maps and topographical charts. For instance, an
elevation map of Gettysburg, Pennsylvania, created in 1874. Using a scanned
copy of the original, Professor Knowles created a highly detailed birds-eye
view of the Civil War battlefield, highlighting strategic features such as buildings,
roads, woods, and hills. By using robust GIS technology on an ordinary laptop
computer, she was able to get the program to run a very complicated, but very
revealing simulation.

Looking at the image, it’s
hard to tell what all the fuss is about. You see elevations, some grayed out as
if in shadow, some illuminated as if by the sun. You see landmarks infamous in
Civil War lore; the Black Horse Tavern, the Union battle line, Little Round
Top. The thing that stands out most, though, is a red dot marking the site of
the Lutheran Seminary; the vantage point from which Confederate General Robert E.
Lee stood to view the battlefield.

The illuminated parts of
the landscape mark terrain that was within General Lee’s field of vision. The
gray bits mark terrain that was hidden from Lee by Gettysburg’s hilly
landscape. The GIS software has provided Professor Knowles (and 150 years of
Civil War scholarship) with scientifically generated insight into Lee’s actions
at the Battle of Gettysburg; actions that led to the Confederacy’s most iconic
defeat.

For military historians,
Robert E. Lee’s disastrous attacks on the second and third days of the battle have
long been enigmatic. General Lee was one of the most celebrated generals on
both sides of the conflict, a masterful commander with military experience
dating back to the Mexican-American War. The terrain around Gettysburg should
have suggested the danger of a frontal assault on Union lines. And yet, he made
this mistake two days in a row.

To explain away Lee’s miscalculation,
Civil War scholars have often criticized his subordinate general James
Longstreet, the commander of the Confederate right. Longstreet has been accused
of everything from incompetence to cowardice for his decision to lead his men
on a protected but circuitous march on their way to attack the Union flank. But
as Professor Knowles has shown, General Longstreet may have been able to see
more of the battlefield and understand more about the tactical situation than
General Lee did.

From his position near
the Black Horse Tavern, Longstreet would have been able to see Union troops on
top of the hill known as Little Round Top, the same hill that Lee had ordered
him to attack. This pair of maps reveals that Lee had a very different
understanding of the battlefield than did his subordinate, resulting in very
different tactical decisions. Longstreet’s protected march may have saved the
lives of hundreds of his own men, but it also delayed Lee’s strategic assault,
allowing the Union line time to advance and prepare their defense.

Professor Knowles points
out that the site where Longstreet’s men engaged the Federal defenders is
illuminated, meaning that is was visible from the Lutheran Seminary. General
Lee’s vantage point would have given him a good view of the bloody skirmish at
the extreme end of the Confederate line, as well as Longstreet’s pained
withdrawal. She speculates that the psychological pain of Lee watching his troops
being killed may have affected his judgment the next day, when he ordered a
costly frontal assault known as Pickett’s Charge.

GIS has also been used
to examine Massachusetts history. The Director of the Salem Witch Trials
Documentary Archive in Virginia, Benjamin Ray, has inserted data on the 1692
witchcraft accusations into an interactive map showing the spread and
distribution of the disturbances. He notes that the progression of the
accusations is similar to that of a disease. You can see the interactive map
here.

And the possibilities of
GIS go beyond historical cartography, as well. Scientists use the program to study
the frequency and pattern of earthquakes. Similar studies are being conducted
on the ozone layer and climate change. On an anthropological note, GIS has been
used to determine that early hunter-gatherer tribes may have deliberately
chosen to settle where they could see the landscape around them, a trait apparently
not shared by agricultural societies.

The purpose of Geographic
Information Systems is to take a range of data far greater than the scope of a
single human being and to put it into a visible, spatial form. In essence, it
visualizes human history, far more effectively and reliably than any painting
or movie ever could. Perhaps even greater achievements lie ahead.

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You can see Professor Knowles' Middlebury College webpage here. Do you think that you have greater strategic and
tactical talents than General Robert E. Lee? If so… are you General James
Longstreet? If so… what’s your secret? How in God’s name are you still alive?
Answers to all these and more can be left in the space below.

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About Aaron M. Dougherty

Aaron is a 2010 graduate of Eastern Michigan University's Master's program in History, with an undergraduate degree in History and Writing. Since 2010, he's worked as a writer, researcher, and historical interpreter for several museums and historical societies in the greater Boston area. Writing this blog is MOSTLY for fun.